brainpopfandomcom-20200223-history
Printers/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby A boy, Tim, sits at his desk, watching a typed letter emerge from his desktop printer. He reads from the typed letter. TIM: Dear Tim and Moby, How is the inkjet printer different from a laser printer? From, Amanda. These two types of printers are both a great way to get what's on your computer onto paper, but they do the job in different ways. Moby is using a paintbrush to paint large dots on a wall. TIM: We'll start with the ink jet. In an ink jet printer, you've got a print head that moves back and forth across the paper in lines, while the paper moves up. An animation shows an ink jet printer's print head at work. TIM: The print head has an ink chamber and rows of nozzles that fire jets of quick-drying ink at the paper. An image shows a close-up of a print head's ink nozzles. TIM: The computer it's connected to sends electrical signals to the nozzles telling them whether or not to fire. An animation shows the process Tim describes. TIM: So ink jet printouts are really a combination of dots and blank spaces. An animation shows an extreme close-up of an ink jet printout of Moby's face. The image is made of dots and blanks. TIM: The further apart the dots, the lighter the image will look. Each nozzle in the print head contains a tube with a tiny heating device inside. The ink fed into the tube is heated up, and a bubble of ink forms. The pressure builds and the bubble expands, until finally ink shoots out onto the paper. An animation shows how the bubble of ink forms and then shoots out of the tube. TIM: Since the ink is still wet when a printout comes out of an ink jet printer, you should be careful not to smudge it. Tim's desktop printer produces a black-and-white printout of Tim, Moby, two female friends, and a mouse. MOBY: Beep. Moby holds up a color printout of the same picture. TIM: Color ink jet printers work in much the same way, firing four different colors instead of just one. Cyan, magenta, yellow, and black inks combine to make a whole rainbow of different colors. The four colors Tim names appear, along with a rainbow of other colors formed by combining those four. TIM: Laser printers are a different story. They receive signals from a computer just like the inkjet, but that's where the similarity ends. The signals are sent to a laser or other light-emitting device that fires pulses of light at a printing drum. This drum is a metal cylinder that is given a negative electrical charge at the beginning of each print cycle. The pulses of light neutralize the drum's charge where they strike it. As the drum rotates, it passes over brushes containing a dark, positively charged powder called toner. An animation shows a laser, pulses of light being fired at the printing drum, and the drum rotating. TIM: Since opposite electrical charges attract, the positive toner sticks to the drum where it's still negatively charged. No toner sticks where the charge has been neutralized by the light-emitting device. The drum rolls over a piece of paper, transferring the toner. A heater seals the toner to the paper, giving you a dry print. A sheet of paper slides under the rotating drum where the toner prints on the paper. Then the paper moves under the heater. MOBY: Beep. TIM: Well, for a color laser print, the drum gets toner powder in four colors instead of just black. MOBY: Beep. Moby points to the wall where he was painting large dots earlier. The dots form an image of Moby's face. TIM: Yeah, I guess it's pretty good, Moby. But it's hardly a masterpiece. It's just a bunch of dots. MOBY: Beep. Category:BrainPOP Transcripts Category:BrainPOP Engineering & Technology Transcripts